Cracked fuel oils stabilized with amine salts of dithiocarbamic acids



United States Patent C) CRACKED FUEL OILS STABILIZED WITH AMINE SALTS OF DITHIOCARBAMIC ACIDS Henry C. Geller, Wilmington, Del., and Bernard Miller Sturgis, Pitman, N.J., assignors to E. I. du Pont de Nemours and Company, Wilmington, Del., :1 corporation of Delaware No Drawing. Application May 1, 1956 Serial No. 581,845

Claims. (Cl. 44-72) Thisinvention is directed to new inhibitors in the form of amine salts of dithiocarbamic acids for fuel oils containing cracked hydrocarbons boiling in the fuel oil range, said inhibitors improving the storage properties of said fuel oils.

Commercial fuel oils, as sold for use in oil burners, furnaces, diesel engines and jet engines, are produced from straight-run hydrocarbon distillates and from pctroleum crudes resulting from thermal and catalyticcracking. Fuel oils are produced more economically and in larger volumes by thermaland catalytic-cracking methods; increased demand for fuel oils is met largely by increased production of cracked stocks.

It is known that fuel oils consisting essentially of or containing in part cracked hydrocarbons are subject to serious discoloration and formation of insoluble. sludge.

during storage. This pronounced instability in contrast to the comparative intertness of straight-run distillates is attributed primarily to oxidation, polymerization and condensation reactions of olefins and diolefins and of sulfur and'nitrogen compounds present in the cracked (particularly catalytic-cracked) fuel oils.

In general, discolored fuel oils as hereinbefore described are objectionable to the trade as certain color standards have to be met in marketing fuel oils. Deposition of insoluble sludge in storage is particularly undesirable in that the deposits plug filter screens, orifices, nozzles, etc.

Special refiningtechniques for improving storage stability of fuel oils involve relatively costly operationsj thus, there is a need for incorporating into said fuel oil relatively small quantities of chemicals as inhibitors against deterioration in storage. a

It is an objectv of the present invention to provide a fuel oil containing catalytic-cracked hydrocarbons boiling in the fuel oil range stabilized against sludge formation and discoloration by incorporating into said fuel oils small quantities of a suitable additive as inhibitor.

More specifically, the present. invention is directed to a fuel. oil containing catalytic-cracked hydrocarbon stocks boiling in the fuel oil range, and, as an inhibitor of discoloration and sludge formation, from 0.001% to 0.5% of a fuel-soluble amine salt of a dithiocarbamic acid, said inhibitor having the formula Where R R R and R are taken from the group consisting of alkyl radicals, cycloalkyl radicals, and alkylene radicals which together with nitrogen constitute a heterocyclic ring, there being a total of at least 5 carbon atoms attached to each nitrogen.

' By fuel oils is meant those hydrocarbon fuels which are heavier than gasoline and adaptable for use in oil furnaces, diesel engines and jet engines.

In addition, by fuel oils containing cracked hydrocarbons boiling in the fuel range is meant catalytic-cracked fuel oils, or blends of straight-run fuel oil distillates and saidcatalytic cracked oils containing about 20% or more of said catalytic-crackedv oils.

Thefuel-soluble amine salts of dithiocarbamic acids of 2,912,314 Patented Nov. 10, 1959.

p o 7 C the present invention are disubstituted-ammonium disubstituted-dithiocarbamates, as indicated in the formula:-

Representative substituents of the alkyl and cycloalkyl type are: methyl, ethyl, nand isopropyl, n-, isoand sec.- butyl, nand isoamyl, hexyl, cyclopentyl, cyclohexyl, cycloheptyl, octyl, decyl, dodecyl, tetradecyl, heptadecyl, octadecyl and the like. 1

, When each nitrogen atom bears two such separate (i.e.,

V monovalent) substituents, the total carbon content of the two groups should be at least 5. One of the substituents may be a methyl group; it is preferred there be at least 4 carbon atoms in each group. a

The substituents attached to nitrogen may be divalent alkylene radicals having at least 5 carbon atoms in the divalent unit, e.g., pentamethylene and hexamethylene, which together with the nitrogen atom form a heterocyclic unit, e.g. piperidino (pentamethyleneimino), and hexa methyleneimino radicals.

It is convenient to name and represent the additives of this invention as salts. It should beunderstood, however, that in non-polar hydrocarbon media, they'may exist as hydrogen-bonded entities with little or no separation of the potentially ionic groups occurring, such as s R,R,N0\- NR3R4 I The fuel-soluble amine salts of dithiocarbamic acids of 9 this invention may be prepared by reacting one mole of carbon disulfide with two moles of a suitable secondary amine. Suitable secondary amines, whichmay be employed singly or as mixtures, are disubstituted ammonia. molecules in which the substituents on nitrogen are alkyl,

' cycloalkyl, or alkylene radicals, as defined. That is, the

v monium methyl-n-butyldithiocarbamate, ethylisopropylammonium ethylisopropyldithiocarbamate, diisopropylammonium diisopropyldithiocarbamate, di-n-butylammonium di-n-butyldithiocarbamate, diisobutylammonium diisobutyldithiocarbamate, dicyclohexylammonium dicyclo hexyldithiocarbamate, cyclohexylethylammoniurn cyclohexylethyldithiocarbamate, dioctadecylammonium dioctadecyldithiocarbamate, piperidinium pentamethylenedithiocarbamate. Compounds representative of the above, and similar compounds encompassed by this invention, are de scribed in the accompanying examples illustrating the present invention. H I H The preferred compounds are: dicyclohexylammoniumdicylohexyldithiocarbamate; diisopropylammonium diisopropyldithiocarbamate; dibutylammonium dibutyldithio-fcarbamate, e.g., in which n-butyl and isobutyl groups are equally present (i.e., prepared from equimolar mixture of di-nand diisobutylamines); diamylammonium diamy; dithiocarbamate, e.g., as prepared from commercial mixed diamylamines. *t

The quantities of amine salts of dithiocarbamic acids selected for use in the fuel oil will depend upon the inuse more than 0.5% of the active ingredients based on 3 the entire weight of the fuel oil to be treated. The preferred range is 0.005 to 0.1%.

The defined stabilizers may be incorporated into the fuel oil simply by adding them to the main body of oil and stirring at ordinary temperatures. In another embodiment of the invention the stabilizer or mixture of stabilizers is incorporated into a carrier, e.g., kerosene or xylene, in high concentrationsnormally about 50% by Weight of the concentrate. This concentrated solution represents the commercial form of the stabilizer to be shipped to the refinery Where it is added to the main body of the fuel oil to be stabilized. To prepare such concentrated solutions, amine salts of high solubility are required. The mixed salt prepared from equimolar quantities of di-nand diisobutylamine is particularly satisfactory for this purpose.

Other valuable amine salts for this purpose are those derived from commercially available mixtures of secondary amines, such as the isomeric dibutylamines, the diamylamines, and, the dicoco amines which are understood to be a mixture of long chain secondary amines (di-n-C to di-n-C prepared from coconut oil. The disubstituted ammonium disubstituted dithiocarbamates obtained from these mixed amines and mixtures of said mixed amines are either low melting solids or liquids having high solubility in hydrocarbons.

The dithiocarbamates of this invention which prevent color and sludge formation may be employed in conjunction with other additives for fuel oils, such as metal deactivators and dispersants for fuel oil sludge.

The following examples illustrate the invention.

EXAMPLE 1 Various catalytically-cracked fuel oil No. 2 distillates (A to D in the table) were inhibited against color deterioration and insoluble residue formation by adding 0.005 weight percent of amine salts of dithiocarbamic acids. The fuels were subjected to a high-temperature accelerated test wherein 600 gram samples in vented glass bottles were stored at 210 F. for 16 hours. After cooling the samples to room temperature, their NPA colors were determined and compared with the original colors according to ASTM Method D155-45T. To determine the quantity of sediment formed, each sample was filtered by suction through a tared sintered glass filter having a 1.125 inch diameter and an average pore size of 14 microns. The filter was washed with heptane, dried and weighed.

The results of these tests were as follows:

Table 1 EFFECT OF 0.005% BY WEIGHT OF AMINE SALTS F DI- THIOCARBAMIC ACIDS ON FUEL OILS AGED AT 210 F. FOR 16 HRS.

I-repaired from dicocoarr'ine by reaction with carbon disulfide.

Dicocoamine lS commercially available as Arnwen 2C and consists substantially of secondary aliphatic amines RRNH Where R has the following approximate composition: n-octyl 8%, n-decyl 5%, n-dodeeyl 47%, n-tetradecyl 18%, n-hexadecyl 8% and n-octadecyl 10%.

As can be seen from these results, the additives of this invention markedly improve resistance to discoloration and formation of insoluble residue of fuel oils showing varying tendencies to discolor and form sludge.

EXAMPLE 2 The procedure of Example 1 was repeated using 0.005% by weight of various amine salts of dithiocarbamic acids in typical samples of catalytically-cracked fuel oil No. 2 distillates, designated as fuel oils E and F in the table below. The results of these tests were as follows:

Table 2 NPA Color Insoluble Test Fuel Additive Residue,

Oil mg./600 g.

Before After l1 E None 2- 4.5- 13.1 12 E dimethylammonium di- 2- 3. 5- 25% methyl dithiocarbamate.

13 E dieyclohexylammonium di- 2- 3- 2.0

cyclohexyl-dithiocarbamate.

14... F None 2- 5- 29.6 15 F diethylammonium diethyl- 2- 4 37.6

dithiocarbamate. (haze) l6 F piperidinium pentamethyb 2- 2.5 6.2

ene dithiocarbamate.

Tests 12 and 15 illustrate compounds which are outside the scope of our invention and which are clearly ineffective stabilizers, particularly against sludge formatron, of these cracked oils.

EXAMPLE 3 The procedure of Example 1 was repeated on samples of catalytically-cracked fuel oil No. 2 distillate containing a dialkylammonium dialkyldithiocarbamate. The results obtained with 0.005% by weight of additive based on the treated fuel oil were as follows:

Table 3 DIBUTYLAMMONIUM DIBUIYLDI'IHIOOARBAMATE AS INHIBITOR IN CRACKED FUEL OIL NPA Color Insoluble Test Additive Residue,

mg./600 g.

Before After nond 1.5 3.5 35.6 dibutylammonium dibutyldithio- 1. 5 2 4. 8

carbamate (prepared from equimolar mixture of di-n-butylamine and diisobutylamine).

EXAMPLE 4 A catalytically-cracked fuel oil was treated with 0.005 weight percent of dicyclohexylammonium dicyclohexyldithiocarbamate and 300 ml. samples, along with untreated samples as controls, were subjected to a low temperature aging test in vented glass bottles, at 110 F., in the dark for 15 weeks. At the end of the aging period, first the NPA color of each sample was determined at room temperature, then the sample was filtered through a sintered glass filter having a 1.25 inch disc with an average pore size of 5 microns. The original container and filter were washed with naphtha. The insoluble residue remaining in the container and filter was dissolved in 1:1 acetone-methanol solutions, and the quantity determined by airjet evaporation according to ASTM Method D52546.

The control samples containing no added stabilizer had color ratings of 5 NPA units (i.e., red-brown), and yielded 33.7 mg. of insoluble residue per ml. of fuel oil, whereas samples of fuel oil containing the dicyclohexylammonium dicyclohexyldithiocarbamate had color ratings of 4.5 NPAunits (i.e., light orange), and had I and C above.

5 produced only 5.7 mg. of insoluble residue per 100 m1. of sample.

EXAMPLE 5 A concentrate containing 50% by weight of mixed dibutylammonium dibutyldithiocarbamates in kerosene was prepared directly as follows:

7.6 parts carbon disulfide were added slowly to a stirred solution of 12.9 parts of di-n-butylamine and 12.9 parts of diisobutylamine in 23.4 parts of kerosene, at 510 C. The addition of carbon disulfide completed, the delivery system was rinsed with 10 parts kerosene and the washings added to the reaction mass. The reaction mass was stirred for one hour at 510 C., was warmed briefly to 45 C., and then allowed to cool to room temperature to obtain a clear yellow liquid product containing 5 active ingredient.

Samples of this concentrate effectively stabilized catalytically-cracked fuel oil No. 2 distillates under conditions of the accelerated aging test (210 F. for 16 hours) described in Example 1.

Before being aged, all samples including the control had NPA color ratings of 1.5. After being aged, the control sample containing no added stabilizer had a color rating of 4 NPA units and yielded 43.0 mg. of insoluble residue for each 600 ml. of sample tested. The fuel oil samples containing from 0.001% to 0.1% by weight of active ingredient, had NPA color ratings of 2 after being aged, and yielded from 3.4 to 6.6 mg. of insoluble residue for 600 ml. of aged sample. Concentrates may be prepared, according to this procedure, by starting with various mixtures of isomeric dibutylamines or isomeric diamylamines. Substantially the same beneficial results are obtained on employing concentrates of these dialkylammonium dialkyldithiocarbamates as inhibitors in the above example.

EXAMPLE 6 Concentrates containing 50% by weight of dialkylammonium dialkyldithiocarbamates in xylene were prepared by reacting the following mixtures of secondary amines with carbon disulfide in the ratio of 2 moles of amine to one mole of carbon disulfide, employing the reaction conditions given in Example 1 The composition of dicocoamine is given in a. footnote to Table 1, Example 1.

I Commercially available mixture of isomeric dramylamlnes.

Catalytically-cracked No. 2 fuel oil was inhibited against color deterioration and insoluble residue formation by adding 0.0025 weight percent active ingredient of the concentrates prepared from amine mixtures A, B The treated fuels were aged as described in Example 1. The results of the tests were as follows:

Table 4 EFFECT 0]? 0.0025 WT. PERCENT DITHIOOARBAMATE O FUEL OIL AGED AT 210 F. FOR 16 HOURS EXAMPLE 7 Concentrates, suitable for use as stabilizers for fuel oil, were prepared by mixing 25 parts of a dialkylr ammonium dialkyldithiocarbamate, 25 partsof. kerosene and '50 parts of a kerosene solution containing 25 parts of a 50/40/ 10 tripolymer of octadecenyl methacrylate (technical) /styrene/beta-diethylaminoethyl methacrylate. Preparation and use in fuel oil of the tripolymer and related polymers which may also be employed'in-conjunction with the additives of the present invention are described in U.S. Patents 2,737,452 and 2,737,496.

For example, Blend X was prepared using di-sec.- butylammonium di-sec.-butyldithiocarbamate. Blend Y was prepared using mixed dibutylammonium dibutyldithiocarbamates obtained by reacting an equimolar mixture of di-n-butylamine and diisobutylamine with carbon disulfide (see Example 5). employed in conjunction with a metal deactivator (MDA) such as N,N'-disalicylidene-1,2-propanediamine, as shown below.

Samples of fuel oil containing catalytically-cracked hydrocarbons boiling in the fuel oil range, with and without stabilizer present, were aged according to the procedure given in Example 1 (210 F., 16 hours). Results of these tests were as follows (Table 5):

Table 5 EFFECT OF CONCENTRATES ON FUEL OIL AGED AT 210 F. FOR 16 HOURS NPA Color Insoluble Fuel Oil Additive Residue,

mg./600 Before After g.

None 2- 5- 5. 8 Blend X +0.0007% MDA 2- 3- 0.6 Blend Y -i-0.0007% MDA 2 3- 1. 4

1 Blends X and Y employed in quantities suifieient to provide 0.005% byl weight, based on the fuel oil, of the dithiocarbamate and of the tripo ymer.

This data shows that the amine salts of the dithiocarbamic acids are extremely effective color stabilizers under conditions of the test in addition to effecting a high reduction in residue formation.

The present invention applies to the stabilization of cracked fuel oils, particularly those entirely composed of catalytic-cracked oil or those containing rather high proportions (at least 20%) of catalytic-cracked oil inasmuch as the catalytic-cracked fuels are notoriously subject to deterioration in storage. An outstanding advantage of this invention is that it provides cracked fuel oils having greatly improved resistance to sludge formation and having improved color stability.

We claim:

1. A fuel oil containing catalytic cracked hydrocarbon stocks boiling in the fuel oil range and from 0.001% to.

0.5% of a fuel-soluble amine salt of a dithiocarbamic acid as inhibitor, said inhibitor having the formula wherein R R R and R are taken from the group consisting of alkyl radicals, cycloalkyl radicals, and alkylene radicals which together with nitrogen constitute a heterocyclic ring, there being a total of at least 5 carbon atoms attached to each nitrogen.

These concentrates may be References Cited'in the file of this patent UNITED STATES PATENTS Faust June 6, 1939 Bergen Mar. 7, 1944 Bergen Oct. 2, 1945 Denison et al. May 14, 1946 Jones Apr. 28, 1953 Cyphers et a1 Aug. 23, 1955 Deger Sept. 10, 1957 UNlTED STATES PATENT OFFICE CERTIFECATE OF CORRECTION Patent N Q 2,9 ,3 4 November 10, 1959 Henry 0h, Geller et ala that error appears in the printed specification It is hereby certified requiring correction and that the said Letters of the above numbered patent Patent should read as corrected below.

vColumn 1, line 30,. for "intertness" reed inertness column 3, line 75, in the footnote to 'lable l, for "7%" read 47% column A, Table 3, under the heading "Additive", first line thereof, for "nond" read home Signed and sealed this 3rd day of May 1%0m Attest:

ROBERT C. WATSON KARL H AXLINE Attesting Officer Commissioner of Patents 

1. A FUEL OIL CONTAINING CATALYTIC CRACKED HYDROCARBON STOCKS BOILING IN TEH FUEL OIL RANGE AND FROM 0.001% TO 0.5% OF A FUEL SOLUBLE AMINE SALT OF A DITHIOCARBAMIC ACID AS INHIBITOR, SAID INHIBITOR HAVING THE FORMULA 